Hydrocarbon

A hydrocarbon contains only carbon and hydrogen. A fatty acid also contains oxygen; calling its long chain a hydrocarbon region does not make the whole fatty acid a hydrocarbon. See IUPAC Gold Book: hydrocarbons.

A fused pair of five-membered carbon rings with formula ${\mathrm{C}}_8{\mathrm{H}}_6$. Its neutral conjugated framework has eight pi electrons. Coordination and reduction alter its electron distribution and allow several metal-binding hapticities.

Two metal fragments attached to the fused ring system are syn when they lie on the same face and anti when they lie on opposite faces. A direct metal–metal bond between adjacent fragments generally requires the syn arrangement.

A ${\mathrm{C}}_8{\mathrm{H}}_8$ hydrocarbon with two more hydrogen atoms than pentalene; double-bond isomers are possible. One and two deprotonations give chemically distinct hydropentalenide and pentalenide charge states.

The monoanionic ${\mathrm{C}}_8{\mathrm{H}}_7^{-}$ coordination ligand obtained by removing one proton from dihydropentalene. An aromatic five-membered portion can bind a metal in an eta-five mode while the fused ring retains an uncoordinated alkene.

The dianion ${\mathrm{C}}_8{\mathrm{H}}_6^{2-}$, with ten pi electrons over the fused framework. The two overlapping five-membered rings must not be counted as two independent cyclopentadienyl donors.

A cage isomer of benzene with one carbon–carbon double bond, conventionally described as tricyclo[3.1.0.0(2,6)]hex-3-ene. Its ideal cage geometry belongs to the C2v molecular point group. Molecular symmetry depends on the full three-dimensional cage rather than the apparent symmetry of a planar skeletal projection.

The hydrocarbon with a three-membered carbon ring and an exocyclic methylene double bond at each vertex. The ideal planar structure belongs to the D3h molecular point group.

The conjugated hydrocarbon with a five-membered ring bearing two endocyclic double bonds and one exocyclic methylene double bond. Its ideal planar structure has the C2v molecular point group.

A conjugated hydrocarbon whose pi-site graph is bipartite: its sites can be divided into two sets with every retained resonance interaction joining opposite sets. The definition refers to the selected nearest-neighbour Hückel model, not simply to a visually alternating Lewis drawing.

An acyclic saturated hydrocarbon. The formula applies to a connected neutral alkane with $n\ge 1$ carbon atoms.

The 2-methylbutan-2-yl group, attached through its tertiary carbon.

A saturated seven-carbon hydrocarbon, ${\mathrm{C}}_7{\mathrm{H}}_{16}$; the normal isomer is a weakly coordinating solvent.

A small branched hydrocarbon with no conventional hydrogen-bond acceptor site. Its transfer into water lacks the compensating polar interactions available to oxygen- or nitrogen-containing comparators.